Pro-ictal EEG scheduling improves the yield of epilepsy monitoring: Validating the use of multiday seizure cycles to optimize video-EEG timing

A significant challenge of video-electroencephalography (vEEG) in epilepsy diagnosis is timing monitoring sessions to capture epileptiform activity. Given the significant consequences of misdiagnosis or delayed diagnosis, new techniques to improve diagnostic yield of vEEG are needed. In this study, we introduce and validate pro-ictal EEG scheduling, a method to schedule vEEG monitoring to coincide with periods of heightened seizure probability as a low-risk approach to enhance the diagnostic yield. A database of long-term ambulatory vEEG monitoring sessions (n=5038) of adults and children was examined. Data from linked electronic seizure diaries were extracted (minimum 10 self-reported events over 12-months) to generate cycle-based estimates of seizure risk. VEEG monitoring sessions coinciding with periods of estimated high-risk were allocated to the high-risk group (adults n=305, children n=82) and compared to remaining studies (baseline: adults n=3586, children n=1065). Test of Proportions and Risk-Ratios (RR) were used to index differences in proportions and likelihood of capturing outcome measures (abnormal report, confirmed seizure and diary event) during monitoring. The impact of clinical and demographic factors (sex, epilepsy-type, medication) was also explored. During vEEG monitoring, the high-risk group was 25% more likely to have an abnormal vEEG report (190/305:62.3% vs 1790/3586:49.9%, RR=1.25, 95% CI[1.137:1.370], p<0.001), 63% more likely to present with a confirmed seizure (56/305:18.4% vs 424/3586:11.3%, RR=1.63, 95% CI[1.265:2.101], p<0.001) and 42% more likely to report an event (153/305:50.2% vs 1267/3586:35.3%, RR=1.420, 95% CI[1.259:1.602], p<0.001). In children, the high-risk group was 93% more likely to have a confirmed seizure (21/82:25.6% vs 141/1065:13.2%, RR=1.93, 95% CI[1.297:2.885], p=0.002). Similar effects were observed across clinical and demographic features. This study provides the first large-scale validation of pro-ictal EEG scheduling in improving the yield of vEEG. This innovative approach offers a pragmatic and low-risk strategy to enhance the diagnostic capabilities of vEEG monitoring, significantly impacting epilepsy management. ### Competing Interest Statement R.E.S., P.J.K., D.P., D.E., M.J.C., M.M., D.R.F. and E.S.N. have employment or a financial interest in Seer Medical Pty. Ltd. The remaining authors have no conflicts of interest. ### Funding Statement This research was supported by Australian National Health and Medical Research Council (Award: 1178220) and the BioMedTech Horizons program (Award: 239). Funding partners were not involved in the study design, data collection, analysis and interpretation of data, the writing of this article or the decision to submit it for publication. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics committee of St Vincent's Hospital Melbourne gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors.